Sidelink cross-carrier csi report

ABSTRACT

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for cross-carrier sidelink channel state information (CSI) reporting. One aspect provides a method for wireless communication by a first user equipment (UE). The method generally includes transmitting, to a second UE, one or more channel state information (CSI) requests on one or more first component carriers (CCs), via one or more sidelink control informations (SCIs) that includes a CSI request flag and receiving, in response to the one or more CSI requests, one or more CSI reports from the second UE on one or more second CCs.

INTRODUCTION

Aspects of the present disclosure relate to wireless communications, andmore particularly, to techniques for configuring sidelink communication.

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,broadcasts, or other similar types of services. These wirelesscommunication systems may employ multiple-access technologies capable ofsupporting communication with multiple users by sharing available systemresources with those users (e.g., bandwidth, transmit power, or otherresources). Multiple-access technologies can rely on any of codedivision, time division, frequency division orthogonal frequencydivision, single-carrier frequency division, or time divisionsynchronous code division, to name a few. These and other multipleaccess technologies have been adopted in various telecommunicationstandards to provide a common protocol that enables different wirelessdevices to communicate on a municipal, national, regional, and evenglobal level.

Although wireless communication systems have made great technologicaladvancements over many years, challenges still exist. For example,complex and dynamic environments can still attenuate or block signalsbetween wireless transmitters and wireless receivers, underminingvarious established wireless channel measuring and reporting mechanisms,which are used to manage and optimize the use of finite wireless channelresources. Consequently, there exists a need for further improvements inwireless communications systems to overcome various challenges.

SUMMARY

One aspect of the present disclosure provides a method for wirelesscommunication by a first user-equipment (UE). The method generallyincludes transmitting, to a second UE, one or more channel stateinformation (CSI) requests on one or more first component carriers (CCs)via one or more sidelink control informations (SCIs) that includes a CSIrequest flag, and receiving, in response to the one or more CSIrequests, one or more CSI reports from the second UE on one or moresecond CCs.

One aspect provides a method for wireless communication by a second UE.The method generally includes receiving, from a first UE, one or morechannel state information (CSI) requests on one or more first componentcarriers (CCs) via one or more sidelink control informations (SCIs) thatincludes a CSI request flag, and transmitting, in response to the one ormore CSI requests, one or more CSI reports to the first UE on one ormore second CCs.

One aspect provides a method for wireless communication by a networkentity. The method generally includes configuring at least one of afirst user-equipment (UE) or a second UE a set of component carriers(CCs) available for cross carrier channel state information (CSI)reporting, and signaling, at least one of the first UE or the second UE,an indication of a first one or more of the CCs to use for sending CSIrequests or a second one or more of the CCs to use for sending CSIreports.

Other aspects provide: an apparatus operable, configured, or otherwiseadapted to perform the aforementioned methods as well as those describedelsewhere herein; a non-transitory, computer-readable media comprisinginstructions that, when executed by one or more processors of anapparatus, cause the apparatus to perform the aforementioned methods aswell as those described elsewhere herein; a computer program productembodied on a computer-readable storage medium comprising code forperforming the aforementioned methods as well as those describedelsewhere herein; and an apparatus comprising means for performing theaforementioned methods as well as those described elsewhere herein. Byway of example, an apparatus may comprise a processing system, a devicewith a processing system, or processing systems cooperating over one ormore networks.

The following description and the appended figures set forth certainfeatures for purposes of illustration.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended figures depict certain features of the various aspectsdescribed herein and are not to be considered limiting of the scope ofthis disclosure.

FIG. 1 is a block diagram conceptually illustrating an example wirelesscommunication network.

FIG. 2 is a block diagram conceptually illustrating aspects of anexample base station and user equipment.

FIGS. 3A-3D depict various example aspects of data structures for awireless communication network.

FIGS. 3E-3F depict various example sidelink communication scenarios.

FIG. 4 illustrates a diagram showing examples for implementing acommunications protocol stack in a radio access network (RAN), inaccordance with certain aspects of the present disclosure.

FIG. 5 is a block diagram that illustrates techniques for implementingcarrier aggregation (CA) in multiple layers of a protocol stack, inaccordance with certain aspects of the present disclosure.

FIGS. 6 and 7 are block diagrams illustrating techniques forimplementing CA, in accordance with certain aspects of the presentdisclosure.

FIG. 8 is a flow diagram illustrating example operations for wirelesscommunication by a first user equipment (UE), in accordance with certainaspects of the present disclosure.

FIG. 9 is a flow diagram illustrating example operations for wirelesscommunication by a second UE, in accordance with certain aspects of thepresent disclosure.

FIG. 10 is a flow diagram illustrating example operations for wirelesscommunication by a network entity, in accordance with certain aspects ofthe present disclosure.

FIG. 11 illustrates an example of cross-carrier CSI reporting forsidelink, in accordance with certain aspects of the present disclosure.

FIGS. 12-13 are call flow diagrams illustrating examples ofcross-carrier CSI reporting for sidelink, in accordance with certainaspects of the present disclosure.

FIG. 14 illustrates example medium access control (MAC) control elements(CE) for cross-carrier CSI reporting for sidelink, in accordance withcertain aspects of the present disclosure.

FIG. 15-17 depict devices with example components capable of performingoperations for cross-carrier CSI reporting, in accordance with aspectsof the present disclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatuses, methods,processing systems, and computer-readable mediums for cross-carrier CSIreporting for sidelink communications.

In some cases, one or more CSI reports may be transmitted or aggregatedon one or more component carriers (CCs) that are different from the CCson which the corresponding CSI requests are received. In such cases, thecomponent carriers may be pre-configured or configured and may includelicensed and/or unlicensed carriers for carrier aggregation. As will bedescribed in greater detail below, the component carriers may be furthersemi-statically selected and activated or dynamically selected andindicated.

In some cases, the CSI reports may be conveyed via multiple CSI MAC CEscorresponding to multiple CSI requests, respectively. In other cases,the CSI reports may be conveyed via one CSI MAC CE that aggregatesmultiple CSI reports corresponding to multiple CSI requests.

The techniques presented herein may be applied in various bands utilizedfor NR. For example, for the higher band referred to as FR4 (e.g., 52.6GHz-114.25 GHz), an OFDM waveform with very large subcarrier spacing(960 kHz-3.84 MHz) is required to combat severe phase noise. Due to thelarge subcarrier spacing, the slot length tends to be very short. In alower band referred to as FR2 (24.25 GHz to 52.6 GHz) with 120 kHz SCS,the slot length is 125 μSec, while in FR4 with 960 kHz, the slot lengthis 15.6 μSec. In some cases, a frequency band referred to as FR2 x maybe used. The techniques may also be applied in the FR1 band (4.1 GHz to7.125 GHz), for example, may be used for channel state information (CSI)feedback, control messages, or on control plane signaling.

Introduction to Wireless Communication Networks

FIG. 1 depicts an example of a wireless communications system 100, inwhich aspects described herein may be implemented.

Generally, wireless communications system 100 includes base stations(BSs) 102 (which may also be referred to herein as access node (AN)102), user equipments (UEs) 104, an Evolved Packet Core (EPC) 160, andcore network 190 (e.g., a 5G Core (5GC)), which interoperate to providewireless communications services.

Base stations 102 may provide an access point to the EPC 160 and/or corenetwork 190 for a user equipment 104, and may perform one or more of thefollowing functions: transfer of user data, radio channel ciphering anddeciphering, integrity protection, header compression, mobility controlfunctions (e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, radio access network (RAN) sharing, multimediabroadcast multicast service (MBMS), subscriber and equipment trace, RANinformation management (RIM), paging, positioning, delivery of warningmessages, among other functions. Base stations may include and/or bereferred to as a gNB, Node B, eNB, an access point, a base transceiverstation, a radio base station, a radio transceiver, or a transceiverfunction, or a transmit reception point (TRP) in various contexts.

Base stations 102 wirelessly communicate with UEs 104 via communicationslinks 120. Each of base stations 102 may provide communication coveragefor a respective geographic coverage area 110, which may overlap in somecases. For example, small cell 102′ (e.g., a low-power base station) mayhave a coverage area 110′ that overlaps the coverage area 110 of one ormore macrocells (e.g., high-power base stations).

The communication links 120 between base stations 102 and UEs 104 mayinclude uplink (UL) (also referred to as reverse link) transmissionsfrom a user equipment 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a user equipment 104. The communication links 120 may usemultiple-input and multiple-output (MIMO) antenna technology, includingspatial multiplexing, beamforming, and/or transmit diversity in variousaspects.

Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player, a camera, a gameconsole, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or othersimilar devices. Some of UEs 104 may be internet of things (IoT) devices(e.g., parking meter, gas pump, toaster, vehicles, heart monitor, orother IoT devices), always on (AON) devices, or edge processing devices.UEs 104 may also be referred to more generally as a station, a mobilestation, a subscriber station, a mobile unit, a subscriber unit, awireless unit, a remote unit, a mobile device, a wireless device, awireless communications device, a remote device, a mobile subscriberstation, an access terminal, a mobile terminal, a wireless terminal, aremote terminal, a handset, a user agent, a mobile client, or a client.

Wireless communication network 100 includes a SL component 198, whichmay configure a UE to perform operations for cross-carrier CSI reportingfor sidelink according to operations 800 of FIG. 8 and/or operations 900of FIG. 9 . Wireless communication network 100 includes a SL component199, which may configure a network entity (e.g., a base station, such asa gNB) to perform operations for (guiding) cross-carrier CSI reportingfor sidelink according to operations 1000 of FIG. 10 .

FIG. 2 depicts aspects of an example base station (BS) 102 and a userequipment (UE) 104.

Generally, base station 102 includes various processors (e.g., 220, 230,238, and 240), antennas 234 a-t (collectively antennas 234),transceivers 232 a-t (collectively transceivers 232), which includemodulators and demodulators, and other aspects, which enable wirelesstransmission of data (e.g., data source 212) and wireless reception ofdata (e.g., data sink 239). For example, base station 102 may send andreceive data between itself and user equipment 104.

Base station 102 includes controller/processor 240, which may beconfigured to implement various functions related to wirelesscommunications. In the depicted example, controller/processor 240includes a SL component 241, which may be representative of SL component199 of FIG. 1 . Notably, while depicted as an aspect ofcontroller/processor 240, a SL component 241 may be implementedadditionally or alternatively in various other aspects of base station102 in other implementations.

Generally, user equipment 104 includes various processors (e.g., 258,264, 266, and 280), antennas 252 a-r (collectively antennas 252),transceivers 254 a-r (collectively transceivers 254), which includemodulators and demodulators, and other aspects, which enable wirelesstransmission of data (e.g., data source 262) and wireless reception ofdata (e.g., data sink 260).

User equipment 104 includes controller/processor 280, which may beconfigured to implement various functions related to wirelesscommunications. In the depicted example, controller/processor 280includes SL component 281, which may be representative of SL component198 of FIG. 1 . Notably, while depicted as an aspect ofcontroller/processor 280, SL component 281 may be implementedadditionally or alternatively in various other aspects of user equipment104 in other implementations.

FIGS. 3A-3D depict aspects of data structures for a wirelesscommunication network, such as wireless communication network 100 ofFIG. 1 . In particular, FIG. 3A is a diagram 300 illustrating an exampleof a first subframe within a 5G (e.g., 5G NR) frame structure, FIG. 3Bis a diagram 330 illustrating an example of DL channels within a 5Gsubframe, FIG. 3C is a diagram 350 illustrating an example of a secondsubframe within a 5G frame structure, and FIG. 3D is a diagram 380illustrating an example of UL channels within a 5G subframe. In someaspects, UEs may be configured to communicate (e.g., via SLcommunications) using the frame format described with respect todiagrams 300, 330, 350, 380. A radio frame (e.g., as shown in diagram300) may have a predetermined duration (e.g., 10 ms) and may bepartitioned into 10 subframes, each of 1 ms, with indices of 0 through9. Each subframe may include a variable number of slots (e.g., 1, 2, 4,8, 16, . . . slots) depending on the SCS, during which SL communicationmay occur. Further discussions regarding FIG. 1 , FIG. 2 , and FIGS.3A-3D are provided later in this disclosure.

Introduction to Sidelink

FIGS. 3E and 3F show diagrammatic representations of example vehicle toeverything (V2X) systems in accordance with some aspects of the presentdisclosure. For example, the UEs shown in FIGS. 3E and 3F maycommunicate via sidelink channels and may perform sidelink CSI reportingas described herein.

The V2X systems, provided in FIGS. 3E and 3F provide two complementarytransmission modes. A first transmission mode, shown by way of examplein FIG. 3E, involves direct communications (for example, also referredto as side link communications) between participants in proximity to oneanother in a local area. A second transmission mode, shown by way ofexample in FIG. 3F, involves network communications through a network,which may be implemented over a Uu interface (for example, a wirelesscommunication interface between a radio access network (RAN) and a UE).As illustrated, UEs 352, 354 may communicate with each other using asidelink (SL) 398.

Referring to FIG. 3E, a V2X system 301 (for example, including vehicleto vehicle (V2V) communications) is illustrated with two UEs 302, 304(e.g., vehicles). The first transmission mode allows for directcommunication between different participants in a given geographiclocation. As illustrated, a vehicle can have a wireless communicationlink 306 with an individual (V2P) (for example, via a UE) through a PC5interface. Communications between the UEs 302 and 304 may also occurthrough a PC5 interface 308. In a like manner, communication may occurfrom a UE 302 to other highway components (for example, highwaycomponent 310), such as a traffic signal or sign (V2I) through a PC5interface 312. With respect to each communication link illustrated inFIG. 3E, two-way communication may take place between elements,therefore each element may be a transmitter and a receiver ofinformation. The V2X system 301 may be a self-managed system implementedwithout assistance from a network entity. A self-managed system mayenable improved spectral efficiency, reduced cost, and increasedreliability as network service interruptions do not occur duringhandover operations for moving vehicles. The V2X system may beconfigured to operate in a licensed or unlicensed spectrum, thus anyvehicle with an equipped system may access a common frequency and shareinformation. Such harmonized/common spectrum operations allow for safeand reliable operation.

FIG. 3F shows a V2X system 351 for communication between a UE 352 (e.g.,vehicle) and a UE 354 (e.g., vehicle) through a network entity 356.These network communications may occur through discrete nodes, such as abase station (for example, an eNB or gNB), that sends and receivesinformation to and from (for example, relays information between) UEs352, 354. The network communications through vehicle to network (V2N)links (e.g., Uu links 358 and 310) may be used, for example, for longrange communications between vehicles, such as for communicating thepresence of a car accident a distance ahead along a road or highway.Other types of communications may be sent by the node to vehicles, suchas traffic flow conditions, road hazard warnings, environmental/weatherreports, and service station availability, among other examples. Suchdata can be obtained from cloud-based sharing services.

In some circumstances, two or more subordinate entities (for example,UEs) may communicate with each other using sidelink signals. Asdescribed above, V2V and V2X communications are examples ofcommunications that may be transmitted via a sidelink. Otherapplications of sidelink communications may include public safety orservice announcement communications, communications for proximityservices, communications for UE-to-network relaying, device-to-device(D2D) communications, Internet of Everything (IoE) communications,Internet of Things (IoT) communications, mission-critical meshcommunications, among other suitable applications. Generally, a sidelinkmay refer to a direct link between one subordinate entity (for example,UE1) and another subordinate entity (for example, UE2). As such, asidelink may be used to transmit and receive a communication (alsoreferred to herein as a “sidelink signal”) without relaying thecommunication through a scheduling entity (for example, a BS), eventhough the scheduling entity may be utilized for scheduling or controlpurposes. In some examples, a sidelink signal may be communicated usinga licensed or unlicensed spectrum or a combination of both licensed andunlicensed spectrums.

Various sidelink channels may be used for sidelink communications,including, a physical sidelink control channel (PSCCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink feedbackchannel (PSFCH). The PSCCH may carry control signaling such as sidelinkresource configurations and other parameters used for datatransmissions, and the PSSCH may carry the data transmissions. The PSFCHmay carry feedback such as channel state information (CSI) related to asidelink channel quality.

Example Protocol Stack

FIG. 4 is a diagram showing examples for implementing a communicationsprotocol stack 400 in a radio access network (RAN), according to aspectsof the present disclosure. The illustrated communications protocol stack400 may be implemented by devices operating in a wireless communicationsystem, such as a 5G NR system (e.g., the wireless communication network100 of FIG. 1 ). In various examples, the layers of the protocol stack400 may be implemented as separate modules of software, portions of aprocessor or application-specific integrated circuit (ASIC), portions ofnon-collocated devices connected by a communications link, or variouscombinations thereof. Collocated and non-collocated implementations maybe used, for example, in a protocol stack for a network access device ora UE. As shown in FIG. 4 , the system may support various services overone or more protocols. One or more protocol layers of the protocol stack400 may be implemented by the BS 102 and/or a UE 104.

As shown in FIG. 4 , the protocol stack 400 is split in the BS 102. Theradio resource control (RRC) layer 405, service data adaptation protocol(SDAP) layer 406, packet data convergence protocol (PDCP) layer 410,radio link control (RLC) layer 415, media access control (MAC) layer420, physical (PHY) layer 425, and radio frequency (RF) layer 430 may beimplemented by the BS 102. For example, a central unit-control plane(CU-CP) 403 and a central unit-user plane (CU-UP) 404 each may implementthe RRC layer 405 or SDAP layer 406 respectively and the PDCP layer 410.A distributed unit (DU) may implement the RLC layer 415 and MAC layer420. The Antenna/Remote Radio Units (AU/RRU) may implement the PHYlayer(s) 425 and the RF layer(s) 430. The PHY layers 425 may include ahigh PHY layer and a low PHY layer. The UE 104 may implement the entireprotocol stack 400 (e.g., the RRC layer 405 for control plane, the SDAPlayer 406 for user plane, the PDCP layer 410, the RLC layer 415, the MAClayer 420, the PHY layer(s) 425, and the RF layer(s) 430).

Introduction on Carrier Aggregation on Sidelink

FIG. 5 is a block diagram that illustrates techniques for implementingcarrier aggregation (CA) which may be supported in some V2X deployments(e.g., LTE V2X), but not others (e.g., NR V2X). As shown, a packet dataconvergence protocol (PDCP) layer (e.g., corresponding to the PDCP layer410 of FIG. 4 ) for a protocol stack 502 (e.g., for transmission) mayinclude robust header compression (ROHC) components 506 and securitycomponents 508. As illustrated, a radio link control (RLC) layer (e.g.,corresponding to the RLC layer 415 of FIG. 4 ) of the protocol stack 502may include segmentation components 510. Further, a media access control(MAC) layer (e.g., corresponding to the MAC layer 420 of FIG. 4 ) of theprotocol stack 502 may include a schedule/priority handling component514, a multiplexer 516, and hybrid automatic repeat request (HARQ)components 518, 519. A protocol stack may include a HARQ component foreach carrier configured for signal transmission (e.g., M carriers, whereM is a positive integer). The scheduling/priority handling component 514may schedule packets for transmission on the carriers. For example, thescheduling/priority handling component 514 may generate a RLC protocoldata unit (PDU), which may be provided to the multiplexer 516 forgenerating a MAC PDU. HARQ components 518, 519 may generate transportblocks (TBs) based on the MAC PDU for transmission on the carriers. Forexample, multiple HARQ components (e.g., HARQ components 518, 519) maybe used to implement carrier aggregation (CA) on two carriers totransmit TBs. That is, multiple TBs may be transmitted on differentcarriers to increase throughput gain. There may be one independent HARQcomponent per carrier used for V2X SL communication and each TB and itspotential HARQ retransmissions may be mapped to a single carrier, insome implementations.

As illustrated, a protocol stack 504 may be implemented for receptionwhich may include a MAC layer having HARQ components 524, a packetfiltering component 522, and a demultiplexing component 520 used toprocess received TBs. The protocol stack 504 may include a HARQcomponent 524 for each carrier (e.g., N carriers, where N is a positiveinteger). As shown, the protocol stack 504 may include an RLC layerhaving reassembly components 512 and a PDCP layer having securitycomponents 508 and ROHC components 506.

In some deployments, such as LTE V2X, SL CA with resource allocation maybe implemented with a BS transmitting downlink control information (DCI)having a carrier indication field (CIF) to indicate a carrier to be usedfor SL. In some implementations, SL CA may use a sensing procedure toselect resources independently on each involved carrier. The samecarrier may be used for all TBs of the same SL process at least untilanother resource re-selection is triggered.

Sidelink Cross-Carrier CSI Reporting

As described above with reference to FIG. 5 , one independent HARQentity per carrier is typically used for V2X sidelink communication andeach TB (and its potential HARQ retransmissions) are typically mapped toa single carrier. This allows multiple TBs to be transmitted in parallelon different carriers for a throughput gain.

Sidelink CA in certain resource allocation modes (e.g., resourceallocation mode 3 with LTE V2X) using a dynamic grant may be consideredas similar to resource allocation on the Uu (cellular) interface, by theuse of a carrier indication field (CIF) in the DCI from the eNB.Sidelink CA in other resource allocation modes (e.g., resourceallocation mode 4 with LTE V2X) uses a sensing procedure to selectresources independently on each involved carrier. The same carrier isused for all transport blocks of the same sidelink process at leastuntil the process triggers resource re-selection. Conventionally, thereis no CSI reporting in LTE V2X and Carrier Aggregation is notconventionally supported in NR V2X.

In the case of CA, the multi-carrier nature of the physical layer istypically only exposed to the MAC layer for which one HARQ entity istypically required per serving cell, as depicted in FIGS. 6 and 7 . FIG.6 illustrates the multi-carrier nature of CA multiplexing of multipleUEs (UE₁. . . UE_(n)) for downlink on Uu interface, while FIG. 7illustrates the multi-carrier nature of CA for a single UE for uplink onUu interface.

As illustrated, in both uplink and downlink, there is typically oneindependent hybrid-ARQ entity per serving cell and one transport blockis generated per assignment/grant per serving cell in the absence ofspatial multiplexing. Each TB and its potential HARQ retransmissions aremapped to a single serving cell. Cross-carrier scheduling and feedbackmay be supported, for example, where a primary cell (Pcell) schedules aDL transmission on a secondary cell (Scell) and receives either HARQfeedback or CSI report, where the scheduling DCI on PDCCH andfeedback(s) on PUCCH or PUSCH are carried on the Pcell's carrier and theDL transmission on PDSCH is carried on the Scell's carrier.

For sidelink communications, Asynchronous Channel State Information (CSI) reporting may be supported for each set of paired UEs with a PC5 RRCconnection (for sidelink unicast) for both Mode 1 and Mode 2 resourceallocation in NR V2X. This asynchronous CSI reporting may be triggeredby one of the paired UEs that sends a sidelink control informationmessage (e.g., a SCI 2 with data) to the other UE with a CSI requestfield set to “1”. The CSI may be reported by the other UE via a MAC CE.

This type of CSI reporting may be constrained by a latency requirementfor a CSI triggering UE via CSI report timer sl-CSI-ReportTimer. Withthe development of more dynamic carrier aggregation (e.g., with carriersoperating at FR2 or mmWave where the channel is more dynamic with deepattenuation and severe blocking or carriers operating at unlicensedspectrum where the channel is more opportunistic than deterministic), aCSI report may not be received due to blocking or unavailable channel.This may potentially cause performance degradation for unicasttransmissions between UEs.

Aspects of the present disclosure, however, provide cross-carrier CSIreporting mechanisms that may help to ensure reliable and timely CSIfeedback based on channel status. This enhanced CSI reporting may beimportant to help meet more stringent reliability and latencyrequirements for supporting advanced V2X services.

The CSI reporting mechanisms proposed herein may be used for Intra-band(component carriers within a same frequency band, e.g., carriers in FR2or FR4 band or carriers in unlicensed band) or Inter-band (componentcarriers in different frequency bands, e.g., carriers in FR1 and FR2 orFR4 band or carriers in licensed and unlicensed band) sidelink CarrierAggregation (CA).

The CSI reporting mechanisms proposed herein may be referred to ascross-carrier because one or more CSI reports may be transmitted oraggregated on one or more component carriers which are different fromthe component carriers on which the CSI requests are received. The CSIreports may be conveyed via multiple CSI MAC CEs corresponding tomultiple CSI requests respectively or a single CSI MAC CE may aggregatemultiple CSI reports corresponding to multiple CSI requests.

FIGS. 8 and 9 are flow diagrams illustrating operations 800 and 900 fromthe perspective of a cross-carrier CSI triggering UE and CSI reportingUE, respectively.

Referring first to FIG. 8 , the operations 800 may be performed, forexample, by a first UE (e.g., the UE 120 a in the wireless communicationnetwork 100) to trigger a cross-carrier CSI report by a second UE. Theoperations 800 may be implemented as software components that areexecuted and run on one or more processors (e.g., controller/processor240 of FIG. 2 ). Further, the transmission and reception of signals bythe UE in operations 800 may be enabled, for example, by one or moreantennas (e.g., antennas 252 of FIG. 2 ). In certain aspects, thetransmission and/or reception of signals by the UE may be implementedvia a bus interface of one or more processors (e.g.,controller/processor 280) obtaining and/or outputting signals.

The operations 800 begin, at 810, by transmitting, to a second UE, oneor more channel state information (CSI) requests on one or more firstcomponent carriers (CCs) via one or more sidelink control informations(SCIs) that includes a CSI request flag. For example, the first UE maysend one or more SCI-2 s with a CSI request field set to “1”. SCI-2generally refers to a second stage SCI in a deployment (e.g., NR V2X)that utilizes 2-stage SCI. Splitting SCI into two stages (1^(st)-stageSCI or SCI-1 and 2^(nd)-stage SCI or SCI-2) has an advantage of singlestage that it allows UEs that are not intended recipients to decode onlySCI-1 for channel sensing purposes (e.g., for determining resourcesreserved for other transmissions), while SCI-2 provides additionalcontrol information used by the intended recipients.

At 820, the UE, receives, in response to the one or more CSI requests,one or more CSI reports from the second UE on one or more second CCs. Aswill be described in greater detail below, the CSI reports may be sentin separate MAC CEs or aggregated in a single MAC CE.

FIG. 9 is a flow diagram illustrating example operations 900 that may beconsidered complementary to operations 800 of FIG. 8 . For example,operations 900 may be performed by a second UE to send a cross-carrierCSI report to a first UE performing operations 800 of FIG. 8 . Theoperations 900 may be implemented as software components that areexecuted and run on one or more processors (e.g., controller/processor280 of FIG. 2 ). Further, the transmission and reception of signals bythe UE in operations 900 may be enabled, for example, by one or moreantennas (e.g., antennas 252 of FIG. 2 ). In certain aspects, thetransmission and/or reception of signals by the UE may be implementedvia a bus interface of one or more processors (e.g.,controller/processor 280) obtaining and/or outputting signals.

The operations 900 begin, at 910, by receiving, from a first UE, one ormore channel state information (CSI) requests on one or more firstcomponent carriers (CCs) via one or more sidelink control informations(SCIs) that includes a CSI request flag. At 920, the second UEtransmits, in response to the one or more CSI requests, one or more CSIreports to the first UE on one or more second CCs.

In some cases, an entity other than the paired UEs may guide (or manage)the cross-carrier CSI reporting. For example, a gNB or a roadside unit(RSU) or lead UE (e.g., of a platoon of UEs) may manage cross-carrierCSI reporting.

FIG. 10 is a flow diagram illustrating example operations 1000 that maybe performed by such an entity to guide cross-carrier CSI reporting. Theoperations 1000 may be implemented as software components that areexecuted and run on one or more processors (e.g., controller/processor240 or 280 of FIG. 2 ). Further, the transmission and reception ofsignals by the UE in operations 1000 may be enabled, for example, by oneor more antennas (e.g., antennas 252 of FIG. 2 ). In certain aspects,the transmission and/or reception of signals by the entity may beimplemented via a bus interface of one or more processors (e.g.,controller/processor 240/280) obtaining and/or outputting signals.

The operations 1000 begin, at 1010, by configuring at least one of afirst user-equipment (UE) or a second UE a set of component carriers(CCs) available for cross carrier channel state information (CSI)reporting. At 1020, the entity signals, at least one of the first UE orthe second UE, an indication of a first one or more of the CCs to usefor sending CSI requests or a second one or more of the CCs to use forsending CSI reports.

Cross-carrier CSI-reporting in accordance with certain aspects of thepresent disclosure may be understood with reference to the diagram shownin FIG. 11 . The diagram illustrates a sequence of operations performedat a CSI triggering UE (e.g., performing operations 800 of FIG. 8 ) anda CSI reporting UE (e.g., performing operations 900 of FIG. 9 ).

As illustrated in FIG. 11 , as a first step (step 1), the CSI triggeringUE triggers CSI reports by sending SCI2s, each containing a CSI requestfield/flag set to “1” on the component carrier(s) pre-configured orconfigured or activated for sidelink CA. The SCI2 may also indicate, viaa CSI Carrier Index for the carrier to be used for transmitting thecorresponding CSI report (e.g., Carrier (i) for sidelink cross carrierCSI report). Each SCI may be transmitted with a transport block (TB) ina given carrier for sidelink CA. For example, SCI2(m) may be sent withTB(m) in a PSSCH on carrier(m) and SCI2(n) may be sent with TB(n) in aPSSCH on carrier(n).

In some cases, the carrier i for transmitting CSI report may beconfigured (or pre-configured). For example, for inter-band SL CA, anFR1 carrier may be configured to carry the CSI report for FR1 and FR2carrier aggregation (in order to increase reliability). Similarly, alicensed carrier may be configured to carry the CSI report for CAinvolving licensed and unlicensed carriers. In some cases, the carrier imay be semi-statically selected and activated, for example, by a basestation via Uu interface or by a special UE (e.g., an RSU or a lead UEor a scheduling UE), a CSI triggering UE, or CSI reporting UE via PC5interface. In some cases, the carrier i may be dynamically selected andindicated in SCI 2, for example, by a scheduling UE, a CSI triggeringUE.

At a second step (step 2), the CSI reporting UE extracts the CSI reportinformation from each of the received SCI2 s. Based on the extractedinformation, the CSI reporting UE generates a CSI report for each CSIrequest (e.g., CSI(m) on carrier m and CSI(n) on carrier n).

At a third step (step 3) the CSI reporting UE generates (composes) oneor more CSI report MAC CEs for the CSI requests for CSI(m) and CSI(n).In some cases, multiple CSI report MAC CEs may be generated for thecorresponding CSI requests on multiple carriers, for example, CSI MACCE(m) for CSI request CSI(m) and CSI MAC CE(n) for CSI request CSI(n).In other cases, a single CSI report MAC CE may aggregate multiple CSIreports, for example, with multiple CSI report fields for the CSIrequests on multiple carriers for sidelink CA.

At a fourth step (step 4), the CSI reporting UE multiplexes the CSIreport MAC CE (or MAC CEs) with other logic channels in a PSSCHtransmission on carrier (i) as illustrated in FIG. 11 .

At a high level, preparation for cross-carrier CSI reporting may involvetwo general stages: Configuring (or pre-configuring) the componentcarriers available for cross-carrier CSI reporting; Selecting (oractivating) one or more of the configured component carriers.

Example details of these different stages are shown in the call flowdiagram of FIG. 12 . In the configuration stage, UEs may bepre-configured or configured via the network (at step 1) while the UEsare under network's coverage, based on service(s), with sidelink CAenabled (e.g., SL-NR-CA), with sidelink component carrier(s) for CSIreporting (e.g., indicated via an SL-NR-CA-carrier-CSI-list), sidelinkcomponent carriers supported or blocked for sidelink CA with CSI request(e.g., via an SL-NR-CA-carrier-list or SL-NR-CA -carrier-combined-listfor sidelink CA with CSI request, SL-NR-CA-carrier-block-list orSL-NR-CA-carrier-combined-block-list blocked for sidelink CA with CSIrequest).

As an alternative, or in addition to network configuration, sidelink CSIreport component carriers may be configured via PC5 RRC.

In this case, at step 2, during PC5 connection establishment between twoUEs (e.g., a CSI triggering UE and a CSI reporting UE) , information maybe exchanged via UE's capability message with sidelink componentcarriers information for CSI reporting (e.g., indicated via anSL-NR-CA-carrier-CSI-ue-list) and/or sidelink component carrierssupported or blocked for sidelink CA with CSI request (e.g., via anSL-NR-CA-carrier-ue-list or SL-NR-CA-carrier-combined-ue-list,SL-NR-CA-carrier-block-ue-list orSL-NR-CA-carrier-combined-block-ue-list), security, and/or radio bearersbased on Quality of Service (QoS) flow.

As an alternative, or in addition, at step 3, the CSI reporting UE maysend a UEAssistancelnformationSidelink message with sidelink componentcarriers information for CSI reporting (e.g., indicated via anSL-NR-CA-carrier-CSI-ue-list) and/or sidelink component carriersinformation for sidelink CA with CSI request (e.g., via anSL-NR-CA-carrier-ue-list or SL-NR-CA-carrier-combined-ue-list,SL-NR-CA-carrier-block-ue-list or SL-NR-CA-carrier-combined-block-ue-list).

At step 4, the CSI triggering UE may determine sidelink componentcarriers for sidelink CA with CSI request (e.g.,SL-NR-CA-carrier-list-1) and/or sidelink CSI report component carrier(s)(e.g., SL-NR-CA-carrier-CSI-list-1) based on the sidelink componentcarrier information received via CSI reporting UE's UE Capabilitymessage (e.g., at step 2) or CSI reporting UE's UE assistanceinformation message (e.g., at step 3), and then send anRRCReconfigurationSidelink message with determined sidelink componentcarriers (e.g., SL-NR-CA-carrier-list1) and/or sidelink CSI reportcomponent carrier(s) (e.g., SL-NR-CA-carrier-CSI-listl). The CSIreporting UE may respond, for example, with anRRCReconfigurationCompleteSidelink message to indicate acceptance (step5A), or with an RRCReconfigurationFailureSidelink message (step 5B) withrejected component carrier(s) (e.g., SL-NR-CA-carrier-block-list2 and/orSL-NR-CA-carrier-CSI-block-list2) or suitable component carrier(s)(e.g., SL-NR-CA-carrier-list2 and/or SL-NR-CA-carrier-CSI-list2). Inthis case, the CSI triggering UE may send anotherRRCReconfigurationSidelink message with sidelink component carriersupdated (e.g., SL-NR-CA-carrier-list3 and/or SL-NR-CA-carrier-CSI-list3)based on CSI reporting UE's rejection and the CSI reporting UE mayaccept the updated configuration via anotherRRCReconfigurationCompleteSidelink message. At this point, theconfiguration stage may be considered complete, as both the CSITriggering UE and CSI Reporting UE are configured with componentcarriers for SL CA and cross-carrier SL CSI reporting.

As an alternative, or in addition, sidelink CA component carriers and/orsidelink CSI report component carriers may be selected and thenconfigured via PC5 RRC or activated via PC5 MAC CE.

In this case, at step 6, the CSI reporting UE (or CSI triggering UEthough not shown in FIG. 12 ) may send a UEAssistancelnformationSidelinkmessage with sidelink CA component carriers and/or sidelink CSI reportcomponent carriers information (e.g., SL-NR-CA-carrier-list4 and/orSL-NR-CA-carrier-CSI-list4).

At step 7, the CSI triggering UE (or CSI reporting UE though not shownin FIG. 12 ) selects the sidelink carriers for sidelink CA and/or forcross-carrier CSI reporting (e.g., SL-NR-CA-carrier-list5 and/or SLNR-CA-carrier-CSI-lists) taking CSI reporting UE's assistanceinformation into consideration for the carrier selection. In some cases,the selection may be based on metrics, such as measured channel busyratio (CBR) or reference signal received power (RSPS) or received signalstrength indicator (RSSI) over (the pre-configured or configured orreceived via UE's capability message or received via UE's assistanceinformation message) carrier candidates (e.g., pre-configured orconfigured SL-NR-CA-carrier-list and/or SL-NR-CA-carrier-CSI-list, orCSI reporting UE's SL-NR-CA-carrier-ue-list and/orSL-NR-CA-carrier-CSI-ue-list) for transmissions and/or feedbackrespectively. In some cases, carriers may be selected for transmissionsand/or CSI report, if the measured metric is above or below a threshold(e.g., depending on the metric). For example, CBR or RSRP or RSSI belowa threshold for a given carrier may prompt sidelink CA with CSI requestor sidelink CSI report using that carrier.

In some cases, selected NR component carriers for sidelink CA with CSIrequest and/or sidelink CSI report may be configured via PC5 RRC, atstep 8A, the CSI triggering UE (or CSI reporting UE though not shown inFIG. 12 ) may send an RRCReconfigurationSidelink message withinformation, such as sidelink CA component carriers and sidelink CSIreport component carrier(s) (e.g., SL-NR-CA-carrier-list6 and/orSL-NR-CA-carrier-CSI-list6). The CSI reporting UE (or CSI triggering UEthough not shown in FIG. 12 ) may respond with anRRCReconfigurationCompleteSidelink message to indicate acceptance.

In other cases, NR component carriers may be activated or deactivatedvia PC5 MAC CE. For example, at step 8B, the CSI triggering UE (or CSIreporting UE though not shown in FIG. 12 ) may send a PC5 MAC CEactivating sidelink CA with CSI request component carriers and/orsidelink CSI report component carrier(s) (e.g., SL-NR-CA-carrier-list6and/or SL-NR-CA-carrier-CSI-list6). At step 9B, the CSI reporting UE (orCSI triggering UE though not shown in FIG. 12 ) may respond with anACK/NACK for the PC5 MAC CE to indicate acceptance.

As an alternative, or in addition, when triggering the cross-carrier CSIreport, the sidelink component carrier(s) for feedback (e.g., one ormore component carriers indicated in SL-NR-CA-carrier-CSI-list7) may beindicated via SCI2. For example, at step 10, the CSI triggering UE maytransmit TB(s) on selected carriers (e.g., SL-NR-CA-carrier-list6, witheach corresponding SCI 2 indicating sidelink CSI report componentcarrier(s) (e.g., SL-NR-CA-carrier-CSI-list7).

At step 11, the CSI reporting UE generates sidelink CSI reports per thereceived CSI requests and, at step 12, the CSI reporting UE sendssidelink CSI report MAC CE(s) on the indicated CSI report carrier(s)(e.g., one or more component carriers indicated inSL-NR-CA-carrier-CSI-list7).

For the cases or alternatives described for FIG. 12 , the messages orcontrol signals exchanged between CSI triggering UE and CSI reporting UEmay be carried on a carrier pre-configured, configured, or selected andactivated for PC5 control plane.

As noted above, in some cases a third entity (separate from the CSITriggering and CSI Reporting UEs) may help guide or manage sidelink CAwith CSI request component carriers and/or sidelink cross-carrier CSIreporting component carriers. For example, as illustrated in FIG. 13 , agNB, roadside unit (RSU) or lead UE (such as platoon lead) or schedulingUE may manage sidelink CA component carriers and/or sidelinkcross-carrier CSI-reporting component carriers, by taking part in one ofthe configuring, selecting/activation, or triggering stages describedabove.

As illustrated (as steps OA and OB), the managing entity, CSI Triggeringand reporting UEs may start a service and receive correspondinginformation, such as QoS information and sidelink component carriersinformation associated with the service.

To configure component carriers for cross-carrier CSI reporting, at step1, the CSI Triggering and Reporting UEs may perform (on the Uu/cellularlink) SIB12 acquisition information (e.g., SL-ConfigCommonNR) from thegNB or SL MIB or SL SI acquisition (on a PC5 link) from an RSU or LeadUE, for sidelink component carriers information of services. If nosidelink component carriers information is acquired at step 1, at step2, the CSI triggering UE (or CSI reporting UE) sends Sidelink UEInformation, Sidelink UE capability information, and/or Sidelink UEAssistance information with the UE's sidelink component carriersinformation of the service, CSI report component carriers information,and the like. If either CSI triggering UE or CSI reporting UE is out ofthe gNB or RSU or Lead UE's coverage (herein as out of coverage UE), theother UE may forward the sidelink CA with CSI request component carriersinformation and/or sidelink CSI report component carriers information,received from the out of coverage UE on sidelink, to gNB (on Uuinterface) or RSU or Lead UE (on PC5 interface).

At step 3A, the managing entity sends an RRC reconfiguration messagewith sidelink CA with CSI request component carrier information and/orsidelink CSI report component carrier information. For example, a gNBvia Uu interface sends an RRCReconfiguration message or an RSU or LeadUE via PC5 interface sends an RRCReconfigurationSidelink message. Atstep 3B, the CSI triggering UE (or CSI reporting UE) sends an RRCReconfiguration Complete message to indicate acceptance (e.g., anRCReconfigurationComplete message to a gNB on Uu interface orRCReconfigurationCompleteSidelink to RSU or Lead UE on PC5 interface).At step 4A, the CSI triggering UE (or CSI reporting UE) forwards thesidelink CA with CSI request component carriers information and/orsidelink CSI report component carriers information (e.g., via anRRCReconfigurationSidelink message with sidelink CA with CSI requestcomponent carriers information and/or sidelink CSI report componentcarriers information, if needed (e.g., if only one of the CSI TriggeringUE or CSI Reporting UE is in communication with the managing entity). Atstep 4B, the CSI reporting UE (or CSI triggering UE) responds with anRRCReconfigurationCompleteSidelink message to indicate acceptance.

As an alternative, or in addition, to activate sidelink CA with CSIrequest component carriers and/or sidelink component carriers forcross-carrier CSI reporting, at step 5A, the managing entity may send aMAC CE or DCI. For example, a gNB may send a MAC CE or DCI3 via Uuinterface or an RSU or lead UE or a scheduling UE may send a PC5 MAC CEvia PC5 interface to activate sidelink CA component carriers and/orsidelink CSI report component carriers. At step 5B, the CSI reporting UE(or CSI triggering UE) sends ACKs for the PC5 MAC CE to indicateacceptance.

At step 6A, the CSI triggering UE (or CSI reporting UE) may forwards theMAC CE for activation, if needed (e.g., if only one of the CSITriggering UE or CSI Reporting UE is in communication with the managingentity). At step 6B, the CSI reporting UE (or CSI triggering UE)responds with an ACK to indicate acceptance.

As an alternative, or in addition, at step 7, the managing entity maysend a dynamic indication of sidelink component carriers. For example, agNB may send a CSI request and CSI report component carrier(s) via DCI3on Uu interface or an RSU or Lead UE or a scheduling UE may send a CSIrequest and CSI report component carrier(s) via SCI2 on PC5 interface.

At step 8, the CSI triggering UE (or CSI reporting UE) sends a CSIrequest and indicates the CSI report component carrier(s) via SCI2 onone or more sidelink carriers.

At step 9, the CSI reporting UE sends the CSI report(s) on the indicatedsidelink component carrier(s).

For the cases or alternatives described for FIG. 13 , the messages orcontrol signals exchanged between a gNB and CSI triggering UE or CSIreporting UE may be carried on a carrier pre-configured, configured, orselected and activated for Uu control plane; the messages or controlsignals exchanged between an RSU or Lead UE or scheduling UE and CSItriggering UE or CSI reporting UE may be carried on a carrierpre-configured, configured, or selected and activated for PC5 controlplane; the messages or control signals exchanged between CSI triggeringUE or CSI reporting UE may be carried on a carrier pre-configured,configured, or selected and activated for PC5 control plane betweenthese two UEs.

As described above, the CSI reports may be sent in separate MAC CEs ormultiple CSI reports could be aggregated in a single MAC CE.

FIG. 14 illustrates two examples of MAC CEs that may aggregate multipleCSI reports. In a first MA CE 1400A, there may be an implicitassociation with CSI requests. For example, CSI reports may be orderedin the MAC CE according to the order of sidelink component carriersassociated with the corresponding CSI requests transmitted by the CSItriggering UE. In a second MAC CE 1400B, there may be an explicitassociation with CSI requests. For example, the MAC CE 1400B may includea Bit Map field that indicates the component carriers associated withCSI reports transmitted by the CSI reporting UE.

While the MAC CE 1400B has an additional field relative to the MAC CE1400A, the signaling overhead may be offset by having a flexible size(as opposed to a possible fixed size of MAC CE 1400A). In other words,the MAC CE 1400B may only include CSI report fields for componentcarriers indicated (e.g., with a corresponding “1” bit) in the Bit Mapfield.

Example Wireless Communication Devices

FIG. 15 depicts an example communications device 1500 that includesvarious components operable, configured, or adapted to performoperations for the techniques disclosed herein, such as the operationsdepicted and described with respect to FIGS. 6-14 . In some examples,communication device 1500 may be a user equipment 104 as described, forexample with respect to FIGS. 1 and 2 .

Communications device 1500 includes a processing system 1502 coupled toa transceiver 1508 (e.g., a transmitter and/or a receiver). Transceiver1508 is configured to transmit (or send) and receive signals for thecommunications device 1500 via an antenna 1510, such as the varioussignals as described herein. Processing system 1502 may be configured toperform processing functions for communications device 1500, includingprocessing signals received and/or to be transmitted by communicationsdevice 1500.

Processing system 1502 includes one or more processors 1520 coupled to acomputer-readable medium/memory 1530 via a bus 1506. In certain aspects,computer-readable medium/memory 1530 is configured to store instructions(e.g., computer-executable code) that when executed by the one or moreprocessors 1520, cause the one or more processors 1520 to perform theoperations illustrated in FIGS. 6-14 , or other operations forperforming the various techniques discussed herein for coordination ofcarrier selection between long term evolution (LTE) and new radio (NR)sidelink (SL).

In the depicted example, computer-readable medium/memory 1530 storescode 1531 (e.g., an example of means for) for transmitting, to a secondUE, one or more channel state information (CSI) requests on one or morefirst component carriers (CCs) via one or more sidelink controlinformations (SCIs) that includes a CSI request flag; code 1532 (e.g.,an example of means for) for receiving, in response to one or more CSIrequests, one or more CSI reports from the second UE on one or moresecond CCs.

In the depicted example, the one or more processors 1520 includecircuitry configured to implement the code stored in thecomputer-readable medium/memory 1530, including circuitry 1521 (e.g., anexample of means for) for transmitting, to a second UE, one or morechannel state information (CSI) requests on one or more first componentcarriers (CCs) via one or more sidelink control informations (SCIs) thatincludes a CSI request flag; circuitry 1522 (e.g., an example of meansfor) for receiving, in response to one or more CSI requests, one or moreCSI reports from the second UE on one or more second CCs.

Various components of communications device 1500 may provide means forperforming the methods described herein, including with respect to FIGS.6-14 .

In some examples, means for transmitting or sending (or means foroutputting for transmission) may include the transceivers 254 and/orantenna(s) 252 of the user equipment 104 illustrated in FIG. 2 and/ortransceiver 1508 and antenna 1510 of the communication device 1500 inFIG. 15 .

In some examples, means for receiving (or means for obtaining) mayinclude the transceivers 254 and/or antenna(s) 252 of the user equipment104 illustrated in FIG. 2 and/or transceiver 1508 and antenna 1510 ofthe communication device 1500 in FIG. 15 .

In some examples, means for providing, means for generating, and/ormeans for selecting may include various processing system components,such as: the one or more processors 1520 in FIG. 15 , or aspects of theuser equipment 104 depicted in FIG. 2 , including receive processor 258,transmit processor 264, TX MIMO processor 266, and/orcontroller/processor 280 (including SL component 281).

Notably, FIG. 15 is just use example, and many other examples andconfigurations of communication device 1500 are possible.

FIG. 16 depicts an example communications device 1600 that includesvarious components operable, configured, or adapted to performoperations for the techniques disclosed herein, such as the operationsdepicted and described with respect to FIGS. 6-14 . In some examples,communication device 1600 may be a user equipment 104 as described, forexample with respect to FIGS. 1 and 2 .

Communications device 1600 includes a processing system 1602 coupled toa transceiver 1608 (e.g., a transmitter and/or a receiver). Transceiver1608 is configured to transmit (or send) and receive signals for thecommunications device 1600 via an antenna 1610, such as the varioussignals as described herein. Processing system 1602 may be configured toperform processing functions for communications device 1600, includingprocessing signals received and/or to be transmitted by communicationsdevice 1600.

Processing system 1602 includes one or more processors 1620 coupled to acomputer-readable medium/memory 1630 via a bus 1606. In certain aspects,computer-readable medium/memory 1630 is configured to store instructions(e.g., computer-executable code) that when executed by the one or moreprocessors 1620, cause the one or more processors 1620 to perform theoperations illustrated in FIGS. 6-14 , or other operations forperforming the various techniques discussed herein for coordination ofcarrier selection between long term evolution (LTE) and new radio (NR)sidelink (SL).

In the depicted example, computer-readable medium/memory 1630 storescode 1631 (e.g., an example of means for) for receiving, from a firstUE, one or more channel state information (CSI) requests on one or morefirst component carriers (CCs) via one or more sidelink controlinformations (SCIs) that includes a CSI request flag; code 1632 (e.g.,an example of means for) for transmitting, in response to the one ormore CSI requests, one or more CSI reports to the first UE on one ormore second CCs.

In the depicted example, the one or more processors 1620 includecircuitry configured to implement the code stored in thecomputer-readable medium/memory 1630, including circuitry 1621 (e.g., anexample of means for) for receiving, from a first UE, one or morechannel state information (CSI) requests on one or more first componentcarriers (CCs) via one or more sidelink control informations (SCIs) thatincludes a CSI request flag; circuitry 1622 (e.g., an example of meansfor) for transmitting, in response to the one or more CSI requests, oneor more CSI reports to the first UE on one or more second CCs.

Various components of communications device 1600 may provide means forperforming the methods described herein, including with respect to FIGS.6-14 .

In some examples, means for transmitting or sending (or means foroutputting for transmission) may include the transceivers 254 and/orantenna(s) 252 of the user equipment 104 illustrated in FIG. 2 and/ortransceiver 1608 and antenna 1610 of the communication device 1600 inFIG. 16 .

In some examples, means for receiving (or means for obtaining) mayinclude the transceivers 254 and/or antenna(s) 252 of the user equipment104 illustrated in FIG. 2 and/or transceiver 1608 and antenna 1610 ofthe communication device 1600 in FIG. 16 .

In some examples, means for providing, means for generating, and/ormeans for selecting may include various processing system components,such as: the one or more processors 1620 in FIG. 16 , or aspects of theuser equipment 104 depicted in FIG. 2 , including receive processor 258,transmit processor 264, TX MIMO processor 266, and/orcontroller/processor 280 (including SL component 281).

Notably, FIG. 16 is just use example, and many other examples andconfigurations of communication device 1600 are possible.

FIG. 17 depicts an example communications device 1700 that includesvarious components operable, configured, or adapted to performoperations for the techniques disclosed herein, such as the operationsdepicted and described with respect to FIGS. 6-14 . In some examples,communication device 1700 may be a user equipment 104 as described, forexample with respect to FIGS. 1 and 2 .

Communications device 1700 includes a processing system 1702 coupled toa transceiver 1708 (e.g., a transmitter and/or a receiver). Transceiver1708 is configured to transmit (or send) and receive signals for thecommunications device 1700 via an antenna 1710, such as the varioussignals as described herein. Processing system 1702 may be configured toperform processing functions for communications device 1700, includingprocessing signals received and/or to be transmitted by communicationsdevice 1700.

Processing system 1702 includes one or more processors 1720 coupled to acomputer-readable medium/memory 1730 via a bus 1706. In certain aspects,computer-readable medium/memory 1730 is configured to store instructions(e.g., computer-executable code) that when executed by the one or moreprocessors 1720, cause the one or more processors 1720 to perform theoperations illustrated in FIGS. 6-14 , or other operations forperforming the various techniques discussed herein for coordination ofcarrier selection between long term evolution (LTE) and new radio (NR)sidelink (SL).

In the depicted example, computer-readable medium/memory 1730 storescode 1731 (e.g., an example of means for) for configuring at least oneof a first user-equipment (UE) or a second UE a set of componentcarriers (CCs) available for cross carrier channel state information(CSI) reporting; and code 1732 (e.g., an example of means for) forsignaling, at least one of the first UE or the second UE, an indicationof a first one or more of the CCs to use for sending CSI requests or asecond one or more of the CCs to use for sending CSI reports.

In the depicted example, the one or more processors 1720 includecircuitry configured to implement the code stored in thecomputer-readable medium/memory 1730, including circuitry 1721 (e.g., anexample of means for) for configuring at least one of a firstuser-equipment (UE) or a second UE a set of component carriers (CCs)available for cross carrier channel state information (CSI) reporting;and circuitry 1722 (e.g., an example of means for) for signaling, atleast one of the first UE or the second UE, an indication of a first oneor more of the CCs to use for sending CSI requests or a second one ormore of the CCs to use for sending CSI reports.

Various components of communications device 1700 may provide means forperforming the methods described herein, including with respect to FIGS.6-14 .

In some examples, means for transmitting or sending (or means foroutputting for transmission) may include the transceivers 254 and/orantenna(s) 252 of the user equipment 104 illustrated in FIG. 2 and/ortransceiver 1708 and antenna 1710 of the communication device 1700 inFIG. 17 .

In some examples, means for receiving (or means for obtaining) mayinclude the transceivers 254 and/or antenna(s) 252 of the user equipment104 illustrated in FIG. 2 and/or transceiver 1708 and antenna 1710 ofthe communication device 1700 in FIG. 17 .

In some examples, means for providing, means for generating, and/ormeans for selecting may include various processing system components,such as: the one or more processors 1720 in FIG. 17 , or aspects of theuser equipment 104 depicted in FIG. 2 , including receive processor 258,transmit processor 264, TX MIMO processor 266, and/orcontroller/processor 280 (including SL component 281).

Notably, FIG. 17 is just use example, and many other examples andconfigurations of communication device 1700 are possible.

Example Clauses

Implementation examples are described in the following numbered clauses:

Clause 1: A method for wireless communication by a first user-equipment(UE), comprising: transmitting, to a second UE, one or more channelstate information (CSI) requests on one or more first component carriers(CCs), via one or more sidelink control informations (SCIs) thatincludes a CSI request flag; and receiving, in response to the one ormore CSI requests, one or more CSI reports from the second UE on one ormore second CCs.

Clause 2: The method of Clause 1, wherein the SCI also includes acarrier index indicating a CC on which a corresponding CSI report is tobe transmitted.

Clause 3: The method of any one of Clauses 1-2, wherein: the one or morefirst CCs are in a first frequency band; and the one or more second CCsare in a second frequency band.

Clause 4: The method of Clause 3, wherein: the first frequency bandcomprises an unlicensed frequency band; and the second frequency bandcomprises a licensed frequency band.

Clause 5: The method of any one of Clauses 1-4, further comprisingsignaling the second UE an indication of the one or more second CCs.

Clause 6: The method of Clause 5, wherein the signaling: semi-staticallyactivates the one or more second CCs; or dynamically indicates the oneor more second CCs.

Clause 7: The method of Clause 5, further comprising selecting at leastone of the one or more first CCs or the one or more second CCs.

Clause 8: The method of any one of Clauses 1-7, further comprisingreceiving signaling, from a wireless entity, indicating the one or moresecond CCs.

Clause 9: The method of Clause 8, wherein the signaling: semi-staticallyactivates the one or more second CCs; or dynamically indicates the oneor more second CCs.

Clause 10: The method of any one of Clauses 1-9, wherein: the one ormore CSI requests comprises multiple CSI requests sent on different CCs;and receiving the one or more CSI reports comprises receiving multipleCSI medium access control (MAC) control elements (CEs), eachcorresponding to one of the CSI requests.

Clause 11: The method of any one of Clauses 1-10, wherein: the one ormore CSI requests comprises multiple CSI requests sent on different CCs;and receiving the one or more CSI reports comprises receiving a CSImedium access control (MAC) control elements (CE) aggregating CSIreports corresponding to the CSI requests.

Clause 12: A method for wireless communication by a seconduser-equipment (UE), comprising: receiving, from a first UE, one or morechannel state information (CSI) requests on one or more first componentcarriers (CCs) via one or more sidelink control informations (SCIs) thatincludes a CSI request flag; and transmitting, in response to the one ormore CSI requests, one or more CSI reports to the first UE on one ormore second CCs.

Clause 13: The method of Clause 12, wherein the SCI also includes acarrier index indicating a CC on which a corresponding CSI report is tobe transmitted.

Clause 14: The method of any one of Clauses 12-13, wherein: the one ormore first CCs are in a first frequency band; and the one or more secondCCs are in a second frequency band.

Clause 15: The method of Clause 14, wherein: the first frequency bandcomprises an unlicensed frequency band; and the second frequency bandcomprises a licensed frequency band.

Clause 16: The method of any one of Clauses 12-15, further comprisingreceiving, from the first UE, an indication of the one or more secondCCs.

Clause 17: The method of Clause 16, wherein the signaling:semi-statically activates the one or more second CCs; or dynamicallyindicates the one or more second CCs.

Clause 18: The method of any one of Clauses 12-17, further comprisingreceiving signaling, from a wireless entity, indicating the one or moresecond CCs.

Clause 19: The method of Clause 18, wherein the signaling:semi-statically activates the one or more second CCs; or dynamicallyindicates the one or more second CCs.

Clause 20: The method of any one of Clauses 12-19, wherein: the one ormore CSI requests comprises multiple CSI requests sent on different CCs;and transmitting the one or more CSI reports comprises transmittingmultiple CSI medium access control (MAC) control elements (CEs), eachcorresponding to one of the CSI requests.

Clause 21: The method of any one of Clauses 12-20, wherein: the one ormore CSI requests comprises multiple CSI requests sent on different CCs;and transmitting the one or more CSI reports comprises transmitting aCSI medium access control (MAC) control elements (CE) aggregating CSIreports corresponding to the CSI requests.

Clause 22: A method for wireless communication by a wireless networkentity, comprising: configuring at least one of a first user-equipment(UE) or a second UE a set of component carriers (CCs) available forcross carrier channel state information (CSI) reporting; and signaling,at least one of the first UE or the second UE, an indication of a firstone or more of the CCs to use for sending CSI requests or a second oneor more of the CCs to use for sending CSI reports.

Clause 23: The method of Clause 22, wherein the signalingsemi-statically activates the one or more second CCs.

Clause 24: The method of any one of Clauses 22-23, wherein the signalingdynamically indicates the one or more second CCs.

Clause 25: The method of any one of Clauses 22-24, wherein: the firstone or more CCs are in a first frequency band; and the second one ormore CCs are in a second frequency band.

Clause 26: The method of Clause 25, wherein: the first frequency bandcomprises an unlicensed frequency band; and the second frequency bandcomprises a licensed frequency band.

Clause 27: An apparatus for wireless communications, comprising meansfor performing the method of any one or more of Clauses 1-26.

Clause 28: An apparatus for wireless communications, comprising a memoryand a processor coupled with the memory, the memory and the processorconfigured to perform the method of any one or more of Clauses 1-26.

Clause 29: A computer-readable medium having instructions stored thereonwhich, when executed by a processor, performs the method of any one ormore of Clauses 1-26.

Additional Wireless Communication Network Considerations

The techniques and methods described herein may be used for variouswireless communications networks (or wireless wide area network (WWAN))and radio access technologies (RATs). While aspects may be describedherein using terminology commonly associated with 3G, 4G, and/or 5G(e.g., 5G new radio (NR)) wireless technologies, aspects of the presentdisclosure may likewise be applicable to other communication systems andstandards not explicitly mentioned herein.

5G wireless communication networks may support various advanced wirelesscommunication services, such as enhanced mobile broadband (eMBB),millimeter wave (mmWave), machine type communications (MTC), and/ormission critical targeting ultra-reliable, low-latency communications(URLLC). These services, and others, may include latency and reliabilityrequirements.

Returning to FIG. 1 , various aspects of the present disclosure may beperformed within the example wireless communication network 100.

In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB)and/or a NB subsystem serving this coverage area, depending on thecontext in which the term is used. In NR systems, the term “cell” andBS, next generation NodeB (gNB or gNodeB), access point (AP),distributed unit (DU), carrier, or transmission reception point (TRP)may be used interchangeably. A BS may provide communication coverage fora macro cell, a pico cell, a femto cell, and/or other types of cells.

A macro cell may generally cover a relatively large geographic area(e.g., several kilometers in radius) and may allow unrestricted accessby UEs with service subscription. A pico cell may cover a relativelysmall geographic area and may allow unrestricted access by UEs withservice subscription. A femto cell may cover a relatively smallgeographic area (e.g., a home) and may allow restricted access by UEshaving an association with the femto cell (e.g., UEs in a ClosedSubscriber Group (CSG) and UEs for users in the home). ABS for a macrocell may be referred to as a macro BS. ABS for a pico cell may bereferred to as a pico BS. A BS for a femto cell may be referred to as afemto BS or a home BS.

Base stations 102 configured for 4G LTE (collectively referred to asEvolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN)) may interface with the EPC 160 throughfirst backhaul links 132 (e.g., an S1 interface). Base stations 102configured for 5G (e.g., 5G NR or Next Generation RAN (NG-RAN)) mayinterface with core network 190 through second backhaul links 184. Basestations 102 may communicate directly or indirectly (e.g., through theEPC 160 or core network 190) with each other over third backhaul links134 (e.g., X2 interface). Third backhaul links 134 may generally bewired or wireless.

Small cell 102′ may operate in a licensed and/or an unlicensed frequencyspectrum. When operating in an unlicensed frequency spectrum, the smallcell 102′ may employ NR and use the same 5 GHz unlicensed frequencyspectrum as used by the Wi-Fi AP 150. Small cell 102′, employing NR inan unlicensed frequency spectrum, may boost coverage to and/or increasecapacity of the access network.

Some base stations, such as gNB 180 may operate in a traditional sub-6GHz spectrum, in millimeter wave (mmWave) frequencies, and/or nearmmWave frequencies in communication with the UE 104. When the gNB 180operates in mmWave or near mmWave frequencies, the gNB 180 may bereferred to as an mmWave base station. The gNB 180 may also communicatewith one or more UEs 104 via a beam formed connection 182 (e.g., viabeams 182′ and 182″).

The communication links 120 between base stations 102 and, for example,UEs 104, may be through one or more carriers. For example, base stations102 and UEs 104 may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100,400, and other MHz) bandwidth per carrier allocated in a carrieraggregation of up to a total of Yx MHz (x component carriers) used fortransmission in each direction. The carriers may or may not be adjacentto each other. Allocation of carriers may be asymmetric with respect toDL and UL (e.g., more or fewer carriers may be allocated for DL than forUL). The component carriers may include a primary component carrier andone or more secondary component carriers. A primary component carriermay be referred to as a primary cell (PCell) and a secondary componentcarrier may be referred to as a secondary cell (SCell).

Wireless communications system 100 further includes a Wi-Fi access point(AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in, for example, a 2.4 GHz and/or 5 GHzunlicensed frequency spectrum. When communicating in an unlicensedfrequency spectrum, the STAs 152/AP 150 may perform a clear channelassessment (CCA) prior to communicating in order to determine whetherthe channel is available.

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink (SL) channels, such as a physical SL broadcast channel (PSBCH),a physical SL discovery channel (PSDCH), a physical SL shared channel(PSSCH), and a physical SL control channel (PSCCH). D2D communicationmay be through a variety of wireless D2D communications systems, such asfor example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on theIEEE 802.11 standard, 4G (e.g., LTE), or 5G (e.g., NR), to name a fewoptions.

EPC 160 may include a Mobility Management Entity (MME) 162, other MMES164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service(MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170,and a Packet Data Network (PDN) Gateway 172. MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. MME 162 is thecontrol node that processes the signaling between the UEs 104 and theEPC 160. Generally, MME 162 provides bearer and connection management.

Generally, user Internet protocol (IP) packets are transferred throughServing Gateway 166, which itself is connected to PDN Gateway 172. PDNGateway 172 provides UE IP address allocation as well as otherfunctions. PDN Gateway 172 and the BM-SC 170 are connected to the IPServices 176, which may include, for example, the Internet, an intranet,an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or otherIP services.

BM-SC 170 may provide functions for MBMS user service provisioning anddelivery. BM-SC 170 may serve as an entry point for content providerMBMS transmission, may be used to authorize and initiate MBMS BearerServices within a public land mobile network (PLMN), and may be used toschedule MBMS transmissions. MBMS Gateway 168 may be used to distributeMBMS traffic to the base stations 102 belonging to a Multicast BroadcastSingle Frequency Network (MBSFN) area broadcasting a particular service,and may be responsible for session management (start/stop) and forcollecting eMBMS related charging information.

Core network 190 may include an Access and Mobility Management Function(AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, anda User Plane Function (UPF) 195. AMF 192 may be in communication with aUnified Data Management (UDM) 196.

AMF 192 is generally the control node that processes the signalingbetween UEs 104 and core network 190. Generally, AMF 192 provides QoSflow and session management.

All user Internet protocol (IP) packets are transferred through UPF 195,which is connected to the IP Services 197, and which provides UE IPaddress allocation as well as other functions for core network 190. IPServices 197 may include, for example, the Internet, an intranet, an IPMultimedia Subsystem (IMS), a PS Streaming Service, and/or other IPservices.

Returning to FIG. 2 , various example components of BS 102 and UE 104(e.g., the wireless communication network 100 of FIG. 1 ) are depicted,which may be used to implement aspects of the present disclosure.

At BS 102, a transmit processor 220 may receive data from a data source212 and control information from a controller/processor 240. The controlinformation may be for the physical broadcast channel (PBCH), physicalcontrol format indicator channel (PCFICH), physical hybrid ARQ indicatorchannel (PHICH), physical downlink control channel (PDCCH), group commonPDCCH (GC PDCCH), and others. The data may be for the physical downlinkshared channel (PDSCH), in some examples.

A medium access control (MAC)-control element (MAC-CE) is a MAC layercommunication structure that may be used for control command exchangebetween wireless nodes. The MAC-CE may be carried in a shared channelsuch as a physical downlink shared channel (PDSCH), a physical uplinkshared channel (PUSCH), or a physical sidelink shared channel (PSSCH).

Transmit processor 220 may process (e.g., encode and symbol map) thedata and control information to obtain data symbols and control symbols,respectively. Transmit processor 220 may also generate referencesymbols, such as for the primary synchronization signal (PSS), secondarysynchronization signal (SSS), PBCH demodulation reference signal (DMRS),and channel state information reference signal (CSI-RS).

Transmit (TX) multiple-input multiple-output (MIMO) processor 230 mayperform spatial processing (e.g., precoding) on the data symbols, thecontrol symbols, and/or the reference symbols, if applicable, and mayprovide output symbol streams to the modulators (MODs) in transceivers232 a-232 t. Each modulator in transceivers 232 a-232 t may process arespective output symbol stream (e.g., for OFDM) to obtain an outputsample stream. Each modulator may further process (e.g., convert toanalog, amplify, filter, and upconvert) the output sample stream toobtain a downlink signal. Downlink signals from the modulators intransceivers 232 a-232 t may be transmitted via the antennas 234 a-234t, respectively.

At UE 104, antennas 252 a-252r may receive the downlink signals from theBS 102 and may provide received signals to the demodulators (DEMODs) intransceivers 254 a-254 r, respectively. Each demodulator in transceivers254 a-254 r may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator may further process the input samples (e.g., for OFDM) toobtain received symbols.

MIMO detector 256 may obtain received symbols from all the demodulatorsin transceivers 254 a-254 r, perform MIMO detection on the receivedsymbols if applicable, and provide detected symbols. Receive processor258 may process (e.g., demodulate, deinterleave, and decode) thedetected symbols, provide decoded data for the UE 104 to a data sink260, and provide decoded control information to a controller/processor280.

On the uplink, at UE 104, transmit processor 264 may receive and processdata (e.g., for the physical uplink shared channel (PUSCH)) from a datasource 262 and control information (e.g., for the physical uplinkcontrol channel (PUCCH) from the controller/processor 280. Transmitprocessor 264 may also generate reference symbols for a reference signal(e.g., for the sounding reference signal (SRS)). The symbols from thetransmit processor 264 may be precoded by a TX MIMO processor 266 ifapplicable, further processed by the modulators in transceivers 254a-254 r (e.g., for SC-FDM), and transmitted to BS 102.

At BS 102, the uplink signals from UE 104 may be received by antennas234 a-t, processed by the demodulators in transceivers 232 a-232 t,detected by a MIMO detector 236 if applicable, and further processed bya receive processor 238 to obtain decoded data and control informationsent by UE 104. Receive processor 238 may provide the decoded data to adata sink 239 and the decoded control information to thecontroller/processor 240.

Memories 242 and 282 may store data and program codes for BS 102 and UE104, respectively.

Scheduler 244 may schedule UEs for data transmission on the downlinkand/or uplink.

5G may utilize orthogonal frequency division multiplexing (OFDM) with acyclic prefix (CP) on the uplink and downlink. 5G may also supporthalf-duplex operation using time division duplexing (TDD). OFDM andsingle-carrier frequency division multiplexing (SC-FDM) partition thesystem bandwidth into multiple orthogonal subcarriers, which are alsocommonly referred to as tones and bins. Each subcarrier may be modulatedwith data. Modulation symbols may be sent in the frequency domain withOFDM and in the time domain with SC-FDM. The spacing between adjacentsubcarriers may be fixed, and the total number of subcarriers may bedependent on the system bandwidth. The minimum resource allocation,called a resource block (RB), may be 12 consecutive subcarriers in someexamples. The system bandwidth may also be partitioned into subbands.For example, a subband may cover multiple RBs. NR may support a basesubcarrier spacing (SCS) of 15 KHz and other SCS may be defined withrespect to the base SCS (e.g., 30 kHz, 60 kHz, 120 kHz, 240 kHz, andothers).

As above, FIGS. 3A-3D depict various example aspects of data structuresfor a wireless communication network, such as wireless communicationnetwork 100 of FIG. 1 .

In various aspects, the 5G frame structure may be frequency divisionduplex (FDD), in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor either DL or UL. 5G frame structures may also be time divisionduplex (TDD), in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 3A and 3C, the 5Gframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and X isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription below applies also to a 5G frame structure that is TDD.

Other wireless communication technologies may have a different framestructure and/or different channels. A frame (10 ms) may be divided into10 equally sized subframes (1 ms). Each subframe may include one or moretime slots. Subframes may also include mini-slots, which may include 7,4, or 2 symbols. In some examples, each slot may include 7 or 14symbols, depending on the slot configuration.

For example, for slot configuration 0, each slot may include 14 symbols,and for slot configuration 1, each slot may include 7 symbols. Thesymbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Thesymbols on UL may be CP-OFDM symbols (for high throughput scenarios) ordiscrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (alsoreferred to as single carrier frequency-division multiple access(SC-FDMA) symbols) (for power limited scenarios; limited to a singlestream transmission).

The number of slots within a subframe is based on the slot configurationand the numerology. For slot configuration 0, different numerologies 0to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe.For slot configuration 1, different numerologies 0 to 2 allow for 2, 4,and 8 slots, respectively, per subframe. Accordingly, for slotconfiguration 0 and numerology μ, there are 14 symbols/slot and 2μslots/subframe. The subcarrier spacing and symbol length/duration are afunction of the numerology. The subcarrier spacing may be equal to2^(μ)×15 kHz, where μ is the numerology 0 to 5. As such, the numerologyμ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has asubcarrier spacing of 480 kHz. The symbol length/duration is inverselyrelated to the subcarrier spacing. FIGS. 3A-3D provide an example ofslot configuration 0 with 14 symbols per slot and numerology μ=2 with 4slots per subframe. The slot duration is 0.25 ms, the subcarrier spacingis 60 kHz, and the symbol duration is approximately 16.67 μs.

A resource grid may be used to represent the frame structure. Each timeslot includes a resource block (RB) (also referred to as physical RBs(PRBs)) that extends 12 consecutive subcarriers. The resource grid isdivided into multiple resource elements (REs). The number of bitscarried by each RE depends on the modulation scheme.

As illustrated in FIG. 3A, some of the REs carry reference (pilot)signals (RS) for a UE (e.g., UE 104 of FIGS. 1 and 2 ). The RS mayinclude demodulation RS (DM-RS) (indicated as Rx for one particularconfiguration, where 100× is the port number, but other DM-RSconfigurations are possible) and channel state information referencesignals (CSI-RS) for channel estimation at the UE. The RS may alsoinclude beam measurement RS (BRS), beam refinement RS (BRRS), and phasetracking RS (PT-RS).

FIG. 3B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol.

A primary synchronization signal (PSS) may be within symbol 2 ofparticular subframes of a frame. The PSS is used by a UE (e.g., 104 ofFIGS. 1 and 2 ) to determine subframe/symbol timing and a physical layeridentity.

A secondary synchronization signal (SSS) may be within symbol 4 ofparticular subframes of a frame. The SSS is used by a UE to determine aphysical layer cell identity group number and radio frame timing.

Based on the physical layer identity and the physical layer cellidentity group number, the UE can determine a physical cell identifier(PCI). Based on the PCI, the UE can determine the locations of theaforementioned DM-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSS and SSS to form a synchronization signal (SS)/PBCH block. TheMIB provides a number of RBs in the system bandwidth and a system framenumber (SFN). The physical downlink shared channel (PDSCH) carries userdata, broadcast system information not transmitted through the PBCH suchas system information blocks (SIBs), and paging messages.

As illustrated in FIG. 3C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. The UE may transmit sounding referencesignals (SRS). The SRS may be transmitted in the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The SRS may be used by a base station for channelquality estimation to enable frequency-dependent scheduling on the UL.

FIG. 3D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. ThePUSCH carries data, and may additionally be used to carry a bufferstatus report (BSR), a power headroom report (PHR), and/or UCI.

Additional Considerations

The preceding description provides examples of NR and LTE sidelinkco-channel co-existence in communication systems. The precedingdescription is provided to enable any person skilled in the art topractice the various aspects described herein. The examples discussedherein are not limiting of the scope, applicability, or aspects setforth in the claims. Various modifications to these aspects will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other aspects. For example, changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in some other examples. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method that is practiced using otherstructure, functionality, or structure and functionality in addition to,or other than, the various aspects of the disclosure set forth herein.It should be understood that any aspect of the disclosure disclosedherein may be embodied by one or more elements of a claim.

The techniques described herein may be used for various wirelesscommunication technologies, such as 5G (e.g., 5G NR), 3GPP Long TermEvolution (LTE), LTE-Advanced (LTE-A), code division multiple access(CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal frequency division multiple access(OFDMA), single-carrier frequency division multiple access (SC-FDMA),time division synchronous code division multiple access (TD-SCDMA), andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, and others. UTRAincludes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA network may implement a radio technology such as NR(e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, andothers. UTRA and E-UTRA are part of Universal Mobile TelecommunicationSystem (UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA,E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from anorganization named “3rd Generation Partnership Project” (3GPP). cdma2000and UMB are described in documents from an organization named “3rdGeneration Partnership Project 2” (3GPP2). NR is an emerging wirelesscommunications technology under development.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a DSP, an ASIC, a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, a system on a chip(SoC), or any other such configuration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userequipment (see FIG. 1 ), a user interface (e.g., keypad, display, mouse,joystick, touchscreen, biometric sensor, proximity sensor, lightemitting element, and others) may also be connected to the bus. The busmay also link various other circuits such as timing sources,peripherals, voltage regulators, power management circuits, and thelike, which are well known in the art, and therefore, will not bedescribed any further. The processor may be implemented with one or moregeneral-purpose and/or special-purpose processors. Examples includemicroprocessors, microcontrollers, DSP processors, and other circuitrythat can execute software. Those skilled in the art will recognize howbest to implement the described functionality for the processing systemdepending on the particular application and the overall designconstraints imposed on the overall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The methods disclosed herein comprise one or more steps or actions forachieving the methods. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims. Further, thevarious operations of methods described above may be performed by anysuitable means capable of performing the corresponding functions. Themeans may include various hardware and/or software component(s) and/ormodule(s), including, but not limited to a circuit, an applicationspecific integrated circuit (ASIC), or processor. Generally, where thereare operations illustrated in figures, those operations may havecorresponding counterpart means-plus-function components with similarnumbering.

The following claims are not intended to be limited to the aspects shownherein, but are to be accorded the full scope consistent with thelanguage of the claims. Within a claim, reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. No claim element is tobe construed under the provisions of 35 U.S.C. §112(f) unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.” All structural and functional equivalents to the elements of thevarious aspects described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims.

What is claimed is:
 1. An apparatus for wireless communications by afirst user-equipment (UE), comprising: a memory; and a processor coupledwith the memory, the memory and the processor configured to: transmit,to a second UE, one or more channel state information (CSI) requests onone or more first component carriers (CCs), via one or more sidelinkcontrol informations (SCIs) that includes a CSI request flag; andreceive, in response to the one or more CSI requests, one or more CSIreports from the second UE on one or more second CCs.
 2. The apparatusof claim 1, wherein the SCI also includes a carrier index indicating aCC on which a corresponding CSI report is to be transmitted.
 3. Theapparatus of claim 1, wherein: the one or more first CCs are in a firstfrequency band; and the one or more second CCs are in a second frequencyband.
 4. The apparatus of claim 3, wherein: the first frequency bandcomprises an unlicensed frequency band; and the second frequency bandcomprises a licensed frequency band.
 5. The apparatus of claim 1,wherein the memory and the processor are further configured to signalthe second UE an indication of the one or more second CCs.
 6. Theapparatus of claim 5, wherein the signaling: semi-statically activatesthe one or more second CCs; or dynamically indicates the one or moresecond CCs.
 7. The apparatus of claim 5, wherein the memory and theprocessor are further configured to select at least one of the one ormore first CCs or the one or more second CCs.
 8. The apparatus of claim1, wherein the memory and the processor are further configured toreceive signaling, from a wireless entity, indicating the one or moresecond CCs.
 9. The apparatus of claim 8, wherein the signaling:semi-statically activates the one or more second CCs; or dynamicallyindicates the one or more second CCs.
 10. The apparatus of claim 1,wherein: the one or more CSI requests comprises multiple CSI requestssent on different CCs; and receiving the one or more CSI reportscomprises receiving multiple CSI medium access control (MAC) controlelements (CEs), each corresponding to one of the CSI requests.
 11. Theapparatus of claim 1, wherein: the one or more CSI requests comprisesmultiple CSI requests sent on different CCs; and receiving the one ormore CSI reports comprises receiving a CSI medium access control (MAC)control elements (CE) aggregating CSI reports corresponding to the CSIrequests.
 12. An apparatus for wireless communications by a seconduser-equipment (UE), comprising: a memory; and a processor coupled withthe memory, the memory and the processor configured to: receive, from afirst UE, one or more channel state information (C SI) requests on oneor more first component carriers (CCs) via one or more sidelink controlinformations (SCIs) that includes a CSI request flag; and transmit, inresponse to the one or more CSI requests, one or more CSI reports to thefirst UE on one or more second CCs.
 13. The apparatus of claim 12,wherein the SCI also includes a carrier index indicating a CC on which acorresponding CSI report is to be transmitted.
 14. The apparatus ofclaim 12, wherein: the one or more first CCs are in a first frequencyband; and the one or more second CCs are in a second frequency band. 15.The apparatus of claim 14, wherein: the first frequency band comprisesan unlicensed frequency band; and the second frequency band comprises alicensed frequency band.
 16. The apparatus of claim 12, wherein thememory and the processor are further configured to receive, from thefirst UE, an indication of the one or more second CCs.
 17. The apparatusof claim 16, wherein the signaling: semi-statically activates the one ormore second CCs; or dynamically indicates the one or more second CCs.18. The apparatus of claim 12, wherein the memory and the processor arefurther configured to receive signaling, from a wireless entity,indicating the one or more second CCs.
 19. The apparatus of claim 18,wherein the signaling: semi-statically activates the one or more secondCCs; or dynamically indicates the one or more second CCs.
 20. Theapparatus of claim 12, wherein: the one or more CSI requests comprisesmultiple CSI requests sent on different CCs; and transmitting the one ormore CSI reports comprises transmitting multiple CSI medium accesscontrol (MAC) control elements (CEs), each corresponding to one of theCSI requests.
 21. The apparatus of claim 12, wherein: the one or moreCSI requests comprises multiple CSI requests sent on different CCs; andtransmitting the one or more CSI reports comprises transmitting a CSImedium access control (MAC) control elements (CE) aggregating CSIreports corresponding to the CSI requests.
 22. An apparatus for wirelesscommunications by a wireless network entity, comprising: a memory; and aprocessor coupled with the memory, the memory and the processorconfigured to: configure at least one of a first user-equipment (UE) ora second UE a set of component carriers (CCs) available for crosscarrier channel state information (CSI) reporting; and signal, at leastone of the first UE or the second UE, an indication of a first one ormore of the CCs to use for sending CSI requests or a second one or moreof the CCs to use for sending CSI reports.
 23. The apparatus of claim22, wherein the signaling semi-statically activates the one or moresecond CCs.
 24. The apparatus of claim 22, wherein the signalingdynamically indicates the one or more second CCs.
 25. The apparatus ofclaim 22, wherein: the first one or more CCs are in a first frequencyband; and the second one or more CCs are in a second frequency band. 26.The apparatus of claim 25, wherein: the first frequency band comprisesan unlicensed frequency band; and the second frequency band comprises alicensed frequency band.
 27. A method for wireless communication by afirst user-equipment (UE), comprising: transmitting, to a second UE, oneor more channel state information (CSI) requests on one or more firstcomponent carriers (CCs), via one or more sidelink control informations(SCIs) that includes a CSI request flag; and receiving, in response tothe one or more CSI requests, one or more CSI reports from the second UEon one or more second CCs.
 28. The method of claim 27, wherein the SCIalso includes a carrier index indicating a CC on which a correspondingCSI report is to be transmitted.
 29. The method of claim 27, wherein:the one or more first CCs are in a first frequency band; and the one ormore second CCs are in a second frequency band.
 30. The method of claim29, wherein: the first frequency band comprises an unlicensed frequencyband; and the second frequency band comprises a licensed frequency band.